Fuel control system



June 5, 1934. J. L. ROTH ET AL FUEL CONTROL SYS TEM Filed Feb. 24. 19322 Sheets-Sheet 1 I r b I l INVENTOR WITNESSES WM 50m Patented June 5,1934 burgh, Pa., assignors to American Heat Economy Bureau, Pittsburgh,Pa., a corporation of Delaware Application ebruary 24, 1932, Serial No.594,974 9 Claims. (01. 13778.)

This invention relates to an improved system of apparatus for regulatingthe flow of liquids and particularlythe flow of liquid fuels to afurnace combustion chamber or the like.

The primary object of the invention generally stated is to provide adependable and comparatively simple system of control for positivelyregulating the rate of flow of liquids through a conduit andparticularly the flow of heavy fuels such as heavyoils, coal tar and thelike to the combustion chamber of an open hearth furnace or similarliquid fuel consumer. V

Another object is to provide apparatus of the character referred to foraccomplishing the aforementioned result which is economical to constructand efficient in operation.

These and other objects as well as the various other novel features andadvantages of the invention will be apparent when the following detaileddescription is read in conjunction with the accompanying drawings ofwhich Fig. 1 is a diagrammatic 1 illustration of a liquid fuel burningfurnace equipped with apparatus constituting one embodiment of theinvention; Fig. 2a a view similar to Fig. 1 illustrating anotherembodiment of the invention; Fig. 2 a vertical section taken on the lineof flow through the rotary valve or pump arranged in the fuel linesleading to the respective furnaces shown in Figs. 1 and 2a; Fig. 3 avertical section of the same taken on the line III-III of. Fig. 2; andFig. 4 a vertical section taken through the pressure-regulating valveemployed'for maintaining a substantially constant pressure drop acrossthe rotary valve as employed in the systems shown in Figs. 1 and 2a.

In the past therehas been considerable difficulty experienced in theregulation of furnaces and burners in which liquid fuels are employed,and especially so where heavy fuels such as heavy oils, coal tar andthelike constitute the fuel. This difficulty has resulted to a veryconsiderable extent from the use of simple variable orifice type valvesfor controlling the flow of such fuels as has been the customarypractice in the past. It has been found that liquids of the nature ofthese fuels have'a tendency to foul and clog up valve orifices sorapidly or otherwise impair their operation that it is practicallyimpossible to satisfactorily regulate the flow of such fuels through theuse of simple valves.

In accordance with this invention, to overcome such difficulties, arotary type metering device such as a freely working rotary pump isemployed as a valve for regulating the flow of ranged between it and themotor.

is uninfiuenced by any variation in pressure in either the fuel lineahead of it or by reason of any variation in the pressure conditionsestablished in the furnace.

Referring to the drawings, and first to Fig. 1, the numeral 1 designatesa furnace to which liquid fuel is furnished by a pipe 3 which may beconnected to any suitable source of supply.

In accordance with the invention a pressure sufficient to force the.fuel into the furnace is exerted on the fuel in this line. Such pressuremay be produced in any suitable manner such for example as by connectingthe pipe to a reservoir having a sufficient elevation to supply thenecessary pressure or by employing a motor driven pump, such as the pump4, which as shown is arranged in the supply line 3 ahead of the furnace.a

For conducting the fuel to the furnace from the pipe or header 3, as itis more commonly known, a pipe 6 is employed. In this pipe a positivedisplacement rotary pump or metering valve 8 is arranged to regulate theflow of fuel to the furnace. This devicemay. be of any suitable type orform having positive displacement characteristics, but is illustratedhere, as shown more particularly in Figs. 2 and 3, as

comprising a well known'form of rotary pump the details of which aredescribed more clearly hereinafter.

For controlling the operation of pump 8 a motor 11 is utilized, and toprovide for varying the speed of the pump with respect to that of themotor a speed-changing device 12 is ar- To render I the rate of flow ofthe fuel in line 6 directly and positively proportionate to the speed ofrotation .of pump 8, a pressure-regulating valve 13 is provided in theline at some suitable point between the pump and the feeder line 3. Thisvalve is adapted to maintain a substantially constant difference inpressure across the pump independently of any pressure variations whichmay occur in the header. As shown in detail in Fig. 4 the valvecomprises a casing 5 having in it an inlet and an outlet chamberseparated by a valve opening in which a valve 18 is arranged to seat. Atthe top of the casing there are located a pair of pressure chambers 14and 15 divided by a flexible diaphragm 16 to which a valve 18 isconnected by a stem 17. The pressure chamber 14 is connected to feedline 6 between valve 13 and pump 8 by a pipe 19, while the chamber 15 isconnected to line 6 between the pump and the furnace by a pipe 21. Withthis arrangement the diaphragm l6 and valve 18 are rendered responsiveto the difference in pressure on the two sides of the pump. Consequentlyit is adapted to automatically determine and maintain a substantiallyconstant difference in pressure across the pump, thus causing the pumpto operate under uniform pressure conditions at all times. With such anarrangement the volume displacement of the pump is directly dependentupon the speed at which the pump is rotated. Accordingly, instead offunctioning as a pump it merely functions as a metering valve and is inno way affected by the variations in pressure in either the feeder line3 or the flow line 6. To provide for varying the difference in pressuredrop across the device 8 a spring 10 may be mounted on the diaphragm 16and a screw 100/. used to determine the pressure the spring exerts uponthe diaphragm.

In the embodiment of the invention illustrated in Fig. 2a, similarreference characters are employed for designating similar parts of theapparatus except for the pump which is referred to by the numeral 9. Inthis modification of the invention instead of utilizing a motor foroperating the pump or metering device 9, as is done in theaforementioned embodiment, a sufficient pressure drop is provided acrossthe pump through the adjustment of the spring 10 on the valve 13 todrive the pump itself as a motor. With such an arrangement, in order toinsure positive control of the pump a positive displacement blower 46,which may have the same details of construction as the pump 9 isconnected to a drive shaft 36 constituting an extension of the driveshaft or the pump to function as a fluid brake. In order to operate thisblower in such a capacity a valve 47 is arranged in its inlet and isoperated by a lever 48. This lever is in turn connected to a pistondisposed in a pressure cylinder 49 connected by a pipe 21 to a pressuretube 37 forming the outlet of the blower. Accordingly, any variations inpressure in tube 37 such as may be produced by variations in the speedof blower 46 by pump 9 are transmitted to the piston of cylinder 49 andthence to the valve 47 with the result that the speed of the pump isprevented from exceeding a preselected value. In an inverse fashion thebraking effort is reduced in a manner to permit the pump to regain itsspeed by reason of the lowering of the pressure in tube 3'7 in case thespeed of the pump falls below its preselected value. Obviously with suchan arrangement the flow of fuel may be increased or decreased in variousways such, for example, as by changing the fulcrum on lever 48 or byarranging a slideway 4811 on the tail end of this lever.

If desired, with a system of this character a meter 42 may be connectedto the tube 37 so as to indicate at all times the pressures produced bythe blower 46 and hence indicate the amount of fuel supplied to thefurnace. Various meters of well known form may be used for this purposeand provided with means for making a graphic record of the pressuresobtaining in the foregoing pressure tube and so calibrated as to recordthe amount of fuel delivered to the furnace per unit of time as well asfor indicating the total amount of fuel supplied during any period ofoperation. Furthermore, if desired, as shown in connection with thecontrol for furnace l a by-pass line 43 may be connected about valve 13and pump 8 so that in case either of these mechanisms fail for anyreason or if for any purpose it is desired to cut them out of the systemthe fuel may be passed around them through this by-pass line. Forcontrolling the flow of fuel when so directed a hand valve 44 isprovided in line 43.

Referring to the details of construction of the pumps and blowersreferred to hereinbefore, reference may be had to Figs. 3 and 4 whereina construction suitable for use as either pump 8 or blower 46 isillustrated. As shown this apparatus comprises a cylindrical casing 51having therein suction and discharge openings 52 and 53 whichcommunicate with inlet and outlet chambers 54 and 55, respectively.These latter chambers are divided by a center plate 56 into twocompartments. Communicating with each of these compartments is a pair'ofpump chambers 5'7 and 58 also of cylindrical form. Through the center ofthese chambers drive shaft 36 is passed, being suitably supported in thecasing. Upon such shaft a pair of annular plungers 59 are eccentricallykeyed, the two being diametrically opposed to each other on oppositesides of partition 56 and adapted to communicate with the walls of thepump chamber as the shaft rotates. Attached to the upper sides ofplungers 59 is a pair of hollow extensions 63 having openings 64 neartheir lower ends and openings 65 in their upper ends, the lattercommunicating with the pump outlet chamber 55 and the former with thecompression chambers on the outlet sides of the rotating plungers. Theseextensions are arranged to move in ball and socket guides 65 and toconnect the pump compression chambers with the ump outlet chambers 55.

In practicing the invention as shown in Fig. l, the motor operated pump4 is first started to provide the necessary pressure in header 3. Thepump motor 11 is then set in motion and the hand valve 67 in pipe 6opened. When this is done the liquid fuel flows into pipe 6 and throughthe pressure regulating valve 13 and rotary valve 8 to the furnace. Atthe starting of this operation valve 13 acts under the influence of theinlet pressure only. However, as soon as the fuel passes valve 8 apressure is set up in pipe 21 causing valve 13 to adjust itselfautomatically to maintain a preselected pressure drop across the pump 8.Hence the amount of fuel supplied thereafter through pipe 6 is def1-nitely proportionate to the speed at which the motor 11 is operated.

With a construction such as that shown in Fig. 2a, after motor 4 hasbeen started and valve 6'7 opened pump 9 will be operated by thepressure in the header 3. The pressure utilized for this purpose will,as in the aforementioned system be positively controlled by theregulating valve 13 as soon as the fuel reaches the pipe 21 inasmuch assuch valve is adapted to maintain the pressure across the pump constant,and, as

previously described, the blower 46 which funcfill tions as a brakethrough the operation of the piston as Will definitely regulate thespeed of the pump 9 and thereby the amount of fuel flowing through thepump.

Among the chief advantages of the invention as referred to above is thatthr ugh its use a flow or fuel through a pipe line may be positively andeffectively regulated independently of any variations which may occur inthe fuel line or in furnace to which fuel is being supplied.

According to the provisions of the patent statutes, We have explainedthe principle and mode of operation of our invention, and haveillustrated and described what We now consider to represent its bestembodiment. However, we desire to have it understood that, Within thescope of the appended claims, the invention may be practiced otherwisethan as specifically illustrated and described.

We claim:

1. A liquid flow control comprising a supply of fluid under pressure, aflow line connected to said supply, a positive displacement valvearranged in said line, means for maintainin a predetermined differencein pressure of substan tially constant value across saidi Valve, andmeans for determining the speed of operation of the valve whereby thevolume or" fluid passing through the flow line is positively determined.

2. A liquid flow regulating system comprising a supply of liquid underpressure, a fiovv line connected to said supply, a positive displacementrotary pump disposed in said flow line, means for maintaining thedifferential in pressure on the two sides of said pump at asubstantially constant predetermined value, and means for controllingthe speed of said pump.

3. A liquid flow regulating system comprising a supply of liquid underpressure, a flow line connected to said supply, a metering valvearranged in said line, a pressure regulating valve disposed in the flowline, pressure responsive for operating said pressure-regulating valve,and means for rendering said pressure responsive means responsive to thediiierential of the pressure obtaining in said how line between saidpressure-regulating valve and said metervalve and the opposite side ofsaid metering valve.

i. A flow control comprising a supply of liquid under pressure, a flowline connected to said liquid supply, a positive displacement pumparranged in said line, a pressure-regulating valve arranged in said flowline and adapted to maintain a substantially constant selected pressuredifference across said pump, and a variable speed motor coupled to thepump for driving it at a selected speed.

5. A flow control comprising a supply of liquid under pressure, a flowline connected to said supply, a positive displacement pump arranged insaid flow line, said pump being adapted to be operated by the pressurein the flow line, means for maintaining the pressure differential on thetwo sides of said pump at a substantially constant preselected value,and means for pr venting said pump exceeding a predetermined speed.

67 A flow control comprising a supply of liquid under pressure, a flowline connected to said supply, a positive displacement pump arranged insaid flow line, said pump being adapted to be operated by the pressurein the flow line, means for maintaining the pressure difiterential onthe two sides of said pump at substantially constant selected value, abraking device coupled to said pump, and means controlled by the speedof said pump for controlling the operation of said brak-- ing device tocontrol the speed of the pump.

'7. A flow control comprising a source of liquid under pressure, a flowline connected to said source of liquid, a positive displacement valvearranged in said flow line and adapted to be driven by the pressure inthe line, a blower coupled to positive displacement valve for producinga force having a definite relation to the speed of the pump, a brakealso coupled to the said valve, and means operated by the pressureproduced by said blower for controlling the operation of said brake.

8. A flow control comprising a source of liquid under pressure, a flowline connected to said source of liquid, a positive displacement rotaryvalve arranged in said flow line and adapted to be driven by thepressure in the line, a pressureregulating valve disposed in said flowline, means for operating said pressure-regulating valve to maintain asubstantially constant preselected pressure drop across the rotaryvalve, a blower operably coupled to the rotary valve and adapted toproduce force bearing a definite relation to the speed of said valve, abrake mechanism for controlling the speed of said rotary valve, andresponsive to the force produced by said blower for controlling theoperation of the brake.

9. A flow control comprising a supply of liquid under pressure, a flowline connected to said supply, a positive displacement rotary valvearranged in said fiovv line for controlling the flow of liquid in theline, means for controlling the speed of said valve, means formaintaining a substantially constant pressure differential across saidpositive displacement valve, and means operated in accordance with thespeed of the valve for recording the volumetric flow of liquid throughthe flow line.

J OSEP -I L. ROTH. WILLIAM R. PAULSEN.

